The first three weeks of May were cool and changeable, and in eastern and southern England very gloomy too, whereas the last ten days of the month were largely dry, warm and sunny.

Mean maximum temperature for May ranged from 18.1C at Heathrow airport to 9.3C at Fair Isle, between Orkney and Shetland, while mean minimum temperature varied between 10.5C at the Olympic Park in London and 2.0C at Altnaharra, Sutherland. Mean monthly temperature was 0.5-1.0 degC below the long-term average in northern Scotland, but 0.5-1.0 degC above in southeast England. The Central England Temperature (CET) of 12.0C was 0.5 0.3 degC above the mean for 1981-2010 - slightly lower than in 2011 but rather higher than in 2010. In the last 100 years 28 Mays were warmer while 72 were colder.

The highest maximum at a standard site in the UK was 29.0C at Cromdale, Morayshire, on the afternoon of the 27th, while the lowest minimum was minus 6.2C at Saughall, Ayrshire, early on the 5th. The lowest daytime maximum was 4.5C at Fair Isle on the 5th, while the warmest night was that of 24th/25th with a minimum of 18.3C at Bute Park in Cardiff.

Rainfall averaged over England and Wales during May was 58mm which is 90 per cent of the average for the standard reference period 1981-2010, the highest for this month for four years; in the last 100 years 55 Mays were wetter while 45 were drier. The equivalent figures for Scotland were 59mm and 99 per cent of the normal amount, and for Northern Ireland 48mm and 85 per cent. Monthly totals at routinely-available sites varied between 158mm at Kinlochewe, Wester Ross, and 12mm at Manston in Kent.

Sunshine averaged over England and Wales during May was 209 hours which is 103 per cent of the 1981-2010 mean; surprisingly it was the dullest May since 2008. In the last 100 years there have been 37 sunnier Mays while 63 have been gloomier. The equivalent figures for Scotland were 242 hours and 135 per cent, and for Northern Ireland 247 hours and 120 per cent. Largest total in the UK was 273 hours at Tiree in the Inner Hebrides and at Fair Isle, and the smallest was 150 hours at Durham.